Skin 101: What is skin?

Skin is our largest organ, but what exactly is it? Dr Jane Sterling, from Addenbrookes hospital in Cambridge joined Graihagh Jackson in the studio. 

Jane - Skin is a wonderful part of the body that works 24/7 to keep us together and working well. It’s a multi-layered surface, so there’s an outside layer - the epidermis - that keeps changing every day; it keeps renewing itself. And then below that is the dermis which gives the skin stretch and strength, and that enables us to move around without the skin splitting every time we bend an elbow or kneel down.

Graihagh - There’s a layer below that as well, isn’t there?

Jane - Yes. There’s the subcutis and that is where the fat is found. So, if you put on a bit of weight and gain some fat, that all sits down in the subcutis and gives the skin extra padding and softness.

Graihagh - I’m sure, which we’re all conscious us as it’s coming through to winter. If I got a cut or something on my hand, how exactly does the skin grow and repair itself?

Jane - Well, it starts immediately. If you cut yourself with a knife, for instance, what you’ll see, of course, is bleeding and that then clots and solidifies and, as soon as that happens, the skin is activated to start repairing itself. New cells come in and start to repair the base of that cut and gradually, over time, strength comes to it and then finally the epidermis comes over after a few days and kind of seals the gap.

But if you have a deep cut like after an operation scar, then that takes a few weeks to a couple of months to regain its full strength. And that’s why they always tell you not to do anything too vigorous after you’ve had an operation so you don’t stretch the scar.

Graihagh - Skin is regenerating all the time isn’t it - it’s not just when you have a cut or anything?

Jane - No. The surface of the skin’s always peeling off. If you get sunburn or something like that you do see the skin peeling off, but all the time we’re losing cells from the surface of the skin. In fact, most of the dust in the house where we live is made up of skin cells that have dropped off our surface and have just accumulated in the corners.

But it’s a very good system because, obviously, we’re rubbing into things and clothes rub the surface of our skin gradually, so the fact that it can repair itself from below is essential otherwise we’d just all be worn away.

Graihagh - How quickly does that regeneration or that process take?

Jane - It’s thought that new skin cells that are made only just a millimetre below the surface that’s at the base of the epidermis, they take about a month to go from the base of the epidermis up to the surface. If you’re younger they move a bit quicker and, like everything else, when you're older they move a bit slower.

Graihagh - I’m thinking of common skin conditions - psoriasis is one that comes to mind. How does that compare to someone, when we’re talking about regeneration, who doesn’t have it?

Jane - Yes. Psoriasis is a fairly common skin disorder and usually seen with red flakey patches, particularly on the knees and elbows and in those patches, the skin is turning over much quicker. The epidermis is turning over quicker, so it takes just about a week for the whole epidermis in those affected areas to renew itself. Of course, if skin’s turning over quicker, it doesn’t make itself quite so perfectly and that’s why the surface is much more obviously flakey and pulls away from the skin quicker.